The balance between beneficial bacteria and yeast and harmful bacteria and yeast in the gastrointestinal (GI) tract dictates not only good GI health, but good health overall. When these powerful microbial forces are out of balance, it can lead to poor health and even disease. Luckily, probiotic dietary supplements (beneficial bacteria and yeast) can help restore this balance and tip the scale back toward good health.
While probiotics primarily impact GI health, their effects don’t stop there. Take immune health. Because more than 70% of our immune system resides in the gut, it’s easy to see why probiotics have such a large influence on immune function.
Ongoing studies suggest that the benefits of probiotics extend far beyond immune and GI health. Science is only scratching the surface of the potential benefits these healthy bugs may impart on systems throughout the body. Some of the areas of probiotic science currently being explored include cognitive function and mental health, dental health, skin health, and heart function.
Mood and Depression
Probiotic species are increasingly being investigated for potential impacts on brain health, including mental health (mood, behavior, etc.). Researchers are now beginning to talk about the existence of a microbiota-gut-brain axis, linking the role of the gut flora with cognitive function.(1)
A recent placebo-controlled evaluation led by Laura Steenbergen from Leiden University (Leiden, The Netherlands) investigated the impact of probiotic supplements on cognitive reactivity to sad mood.(2) In the four-week study, 40 healthy young adults without mood disorder were randomized to twice-daily dosages of a placebo or a probiotic supplement consisting of 2.5 billion colony forming units (CFU). The probiotic supplement contained a mixture of the following bacterial strains: Bifidobacterium bifidum W23, B. lactis W52, Lactobacillus acidophilus W37, L. brevis W63, L. casei W56, L. salivarius W24, and Lactococcus lactis (W19 and W58). Pre- and post-study, the participants filled out a questionnaire that aimed to evaluate cognitive reactivity to sad mood and symptoms of depression and anxiety; in other words, the questionnaire attempted to assess a person’s vulnerability to depression.
Compared to placebo subjects, the participants taking the probiotic supplement scored significantly lower on cognitive reactivity to depression and exhibited less aggressive and ruminative thoughts in response to sad mood. While further studies are needed to confirm these benefits, the findings of the current study are promising and show that probiotics may not only influence brain health; they could play a role in preventing depression and anxiety.
1. Li D et al., “The gut microbiota: A treasure for human health,” Biotechnology Advances. Published online August 31, 2016.
2. Steenbergen L et al., “A randomized controlled trial to test the effect of multispecies probiotics on cognitive reactivity to sad mood,” Brain, Behavior, and Immunity, vol. 48 (August 2015): 258–264
Dental caries, or tooth decay, are a common public health issue affecting millions worldwide. Tooth decay in early life can lead to the complete destruction of teeth and cause infections, pain, and nutritional deficiencies—and even contribute to speech and learning difficulties. Probiotic bacteria are thought to help prevent tooth decay by correcting imbalances in oral bacteria.
A recent study in children aged 2-3 from 16 nursery schools in Chile assessed the benefits of supplementing with a probiotic species, with the goal of preventing tooth decay.(3) Researchers from the University of Chile (Santiago, Chile) randomized 261 children to consume daily (on weekdays) either standard milk or 150 ml of milk containing the probiotic Lactobacillus rhamnosus SP1 (107 CFU/ml). The duration of the study was 10 months.
The prevalence of dental caries decreased in the probiotic group versus those consuming standard milk. The percentage of new individuals who developed caries was 9.7% in the probiotic group and 24.3% in the control group, a statistically significant difference. Within each group, the development of new cavities over the 10-month period averaged 1.13 in the probiotic-supplemented milk group versus 1.75 in the standard milk group. These findings suggest a substantial benefit of probiotic bacteria in helping to reduce the development of dental caries in young children.
3. Rodríguez G et al., “Probiotic compared with standard milk for high-caries children: A cluster randomized trial,” Journal of Dental Research, vol. 95, no. 4 (April 2016): 402–407
Acne and Skin Health
Probiotic supplements can benefit skin health as well by improving the regulation of bodily systems that support healthy skin.
In those with acne, specifically, irregular insulin signaling and overall insulin function are thought to contribute to the progression of skin lesions. A recent double-blind, placebo-controlled pilot study investigated the benefits of the probiotic Lactobacillus rhamnosus SP1 for acne lesions as well as insulin-signaling pathways.(4) Led by Gabriella Fabbrocini of the University of Naples Federico II (Naples, Italy), researchers asked 20 adults with acne to consume a liquid supplement containing Lactobacillus rhamnosus SP1 (3 billion CFU/day), or a placebo, for 12 weeks. Two genetic markers of insulin signaling in skin—insulin-like growth factor 1 (IGF1) and forkhead box protein O1 (FOXO1)—were evaluated before and after probiotic treatment.
Probiotic supplementation resulted in significant improvements in both markers, indicating normalized insulin signaling in skin. Treatment with the probiotic also improved physician ratings of acne lesions compared to placebo.
4. Fabbrocini G et al., “Supplementation with Lactobacillus rhamnosus SP1 normalises skin expression of genes implicated in insulin signalling and improves adult acne,” Beneficial Microbes. Published online September 6, 2016.
Over the past decade, probiotics have been increasingly studied for potential benefits for blood lipid metabolism. It is thought that probiotic bacteria and their metabolites can interact with genes, affecting the expression of proteins involved in the regulation of blood lipid levels. In addition, increased overall inflammation due to imbalances in intestinal flora may also adversely affect heart health. But researchers believe that probiotics may shore up heart health by normalizing intestinal flora and thereby impacting the expression of inflammatory cytokines and other chemicals related to inflammation.
An interesting Brazilian study led by Annelise Costanza of Federal Fluminense University (Niteroi, Brazil) looked at the impact of supplementation with the probiotic yeast Saccharomyces boulardii in heart-failure patients.(5) The placebo-controlled trial was conducted on 20 outpatients who had experienced heart failure (NYHA class II or III, signifying moderate heart failure) with a left ventricular ejection fraction < 50%. These subjects were asked to consume 1000 mg per day of S. boulardii, or a placebo, for three months. Drug treatments for heart failure were left unchanged.
Supplementation with the yeast probiotic was found to significantly improve total cholesterol, uric acid levels, left atrial diameter, and left ventricular ejection fraction. Furthermore, high-sensitivity C-reactive protein (hsCRP), a marker of inflammation, was reduced compared to placebo. Thus, supplementation was found to improve heart function, to favorably affect total cholesterol levels, and to reduce inflammation, all important factors for heart health.
5. Costanza AC et al., “Probiotic therapy with Saccharomyces boulardii for heart failure patients: A randomized, double-blind, placebo-controlled pilot trial,” International Journal of Cardiology. Published online November 11, 2014.